A certain fluorine-containing silane compound is known to be able to provide excellent water-repellency, oil-repellency, antifouling property, or the like when it is used on a surface treatment of a base material. A layer formed from the surface treatment composition comprising a fluorine-containing silane compound is applied to various base materials such as a glass, a plastic, a fiber and a building material as a so-called functional thin film.
Conventionally, in particular, in use of an optical member, a base material formed of an inorganic glass has been used. In order to prevent adhering of a fouling such as fingerprints, a layer is formed by using a fluorine containing compound on the base material as an antifouling coating. As such fluorine containing compound, a surface treatment composition comprising a fluorine containing silane compound having a perfluoropolyether group and a hydroxyl group or a hydrolyzable group which bind to Si as an active ingredient is known (Patent Literature 1). However, in this case, since a bonding between a silanol group and a hydroxyl group are used, the base material is limited to glass, silicon, a metal oxide film, or the like.
On the other hand, recently, use of transparent plastics such as acrylic resin and polycarbonate has been expanded as a material in place of the inorganic glass since they are lightweight and processing of them is easy. It is desired to form the antifouling coating also when the resin material is used. However, since the fluorine containing silane compound as described in Patent Literature 1 is not conformable to the base material formed of the resin material, it is hard to fix on the surface of the base material. As a method of forming a layer less subjected to peeling on a surface of a base material formed of various materials such as resin, a method using a surface treatment composition comprising an acrylic hard coating agent and a perfluoropolyether derivative compatible and copolymerizable with the acrylic hard coating agent is known (Patent Literature 2).